Abstract

The efficiency with which an electromagnetic sensor array is able to distinguish density and ash content of coal and shale mixtures was determined experimentally. The investigated sensor was originally designed for automatic metal detection and sorting in industrial glass recycle processing, where it is widely applied. In coal preparation, the results indicate good possibilities to remove automatically the remaining shale from the coal product, or to recover the remaining coal from the waste rock. Compared to alternative methods, the system has advantages of simple construction, insensitivity to fluctuating dust or moisture levels and a proven industrial reference. Applications can be either sorting of lump-sized coal or coal separation in the 10–50mm size range in a dry preparation process.